A dimmable fluorescent lamp is needed for a long time. Unlike an incandescence lamp in which a common silicon controlled rectifier (SCR) is employed to effect dimming, a fluorescent lamp is a nonlinear load and exhibits a negative resistance characteristic such that the dimming cannot be correspondingly effected in the same manner. In the available domestic and commercial dimmers a TRIAC is usually employed, and a characteristic of which is the requirement of a holding current for maintaining the on state thereof after it has been triggered. The characteristic suits the operation modes of a resistive load such as an incandescence lamp so well but being undesired by a capacitive load such as a fluorescent lamp for the reason that blinking might occur and a proper working state thereof might not be maintained in course of dimming while such dimmers are employed, which in turns has an adverse effect on the life span of the fluorescent lamp.
There is a need for dimmers in a variety of places under various circumstances in daily life, whereby a number of SCR dimmers have already been installed in different places. It is thus desirable for a dimmable fluorescent lamp adapted for such dimmers and it is also preferable to effect dimming by means of a regular light switch in those places without such dimmers.